Offer choice when only VALUELIST is present

[eduard93]

Currently both are required to work.

[eduard93]

Currently this is a required:
Property string As %String(DISPLAYLIST = ",fill,box", DISPLAYNAME = "Строка", VALUELIST = ",fill,box");

But this should also work:
Property string As %String(DISPLAYNAME = "Строка", VALUELIST = ",fill,box");